“…Later research looked at deeper structural and cognitive variables such as propositional density and coherence for predicting text readability (e.g., Crossley, Greenfield, & McNamara, ; Graesser, McNamara, Louwerse, & Cai, ; Kintsch et al, ; McNamara, Louwerse, McCarthy, & Graesser, ). Recent research has focused on the separate and combined effects of lexical (Crossley, Dufty, McCarthy, & McNamara, ; Flor, Klebanov, & Sheehan, ; Lu, Gamson, & Eckert, ), morphological (François & Watrin, ; Hancke, Vajjala, & Meurers, ), psycholinguistic (Boston, Hale, Kliegl, Patil, & Vasishth, ), semantic (vor der Brück, Hartrumpf, & Helbig, ), syntactic (Heilman, Collins‐Thompson, Callan, & Eskenazi, ), and cognitive (Feng, ; Feng, Elhadad, & Huenerfauth, ; Flor & Klebanov, ; Foltz, Kintsch, & Landauer, ; Graesser, McNamara, & Kulikowich, ; Wolfe et al, ) features on readability by making use of the latest development in Natural Language Processing (NLP) technologies and Machine Learning (ML) methods. Although more and more linguistic and cognitive features have been incorporated into the readability assessment models, it was found that the semantic variable of word difficulty accounts for the greatest percentage of readability variance (Marks, Doctorow, & Wittrock, ).…”